It seems to be as I was afraid it would be, when people started to report this more than year ago.
Seems they did not address this meanwhile, which I do not understand. They prepare flagship device HW and developers SW tool, or watch firmware is not supporting it to the fullest.
Actually I can not test it, since I did not want new device with the silly wear OS and hoped Samsung would get rid of it later on, but it seems they are fully invested. Seeing this issue being still around makes me sad, that I was right back then.
I must apologize, when I mentioned canvas before, it was more of a logical assumption, how would it make sense for the max project resolution not being updated with new watches coming out with better resolution. When opening new project it still proudly states its size will be fitted to 450 pixels square. And while the old version at least had there the clickable field to pick resolution, even though there was only one, the newest one does not even try to suggest there could be an option someday.